Light paraffins produced alongside tight oil and natural gas are typically of lesser value than olefins or liquid fuels, and increased production of these light paraffins from U.S. shale formations has created a market surplus of natural gas liquids (NGL). After being extracted in the field, a largely de-methanized NGL stream largely comprising C2-C7 hydrocarbons (also called Y-grade), is typically transported by pipelines from the production site to a fractionation facility where the NGL stream is separated into discrete components, including ethane, propane, iso-butane, n-butane, and natural gasoline (C5+).
Several commercial upgrading options exist for these various components. Some techniques utilize an initial steam cracking step to upgrade these light paraffins, either individually or as a mixture. Other processes instead utilize catalytic processing in various forms. For example Oleflex™, STAR™, Catofin™, or FBD™ can be employed for propane and heavier paraffins, but require removal of ethane prior to upgrading of the heavier NGL components. This requirement is a disadvantage of these technologies, as is their high capital expense. As a result, commercial alternatives are not currently attractive. Accordingly, a need exists for a more efficient process that allows efficient upgrading of a mixture of C2-C7 light olefins (e.g., Y-grade or natural gas liquids) to liquid transportation fuels without first separating out one or more components.